1. Field of the Invention
This invention relates generally to a method of fabricating single crystal semiconductor wafers and, more particularly, to a method of fabricating single crystal diamond semiconductor wafers including cutting the semiconductor wafers from a large single crystal boule of diamond.
2. Discussion of the Related Art
The fabrication and use of diamond semiconductors is known in the art. Although diamond semiconductors are relatively costly to produce, they have a number of distinct advantages over other types of well known semiconductors, such as gallium arsenide semiconductors, which make them an attractive alternative for many applications. These advantages include at least high thermoconductivity providing for the effective removal of waste heat in a semiconductor device incorporating a diamond semiconductor. Consequently, higher thermoconductivity allows generation and dissipation of higher power. Additionally, diamond has a relatively large bandgap, thus providing a more reliable device with a higher signal-to-noise ratio.
Polycrystalline diamond semiconductors provide a device for at least partially realizing the advantages discussed above. However, a polycrystalline structure in and of itself provides a number of drawbacks. One of these drawbacks is the limitations of control of the current flow through a polycrystalline diamond semiconductor device due to the inconsistent orientation of the lattice structure.
In order to provide a worthwhile diamond semiconductor, it is believed to be necessary to utilize single crystal diamond in order to provide for a more reliable flow of electrons through the semiconductor. Because it is very difficult to provide carbon in a liquid form, the known methods of generating single crystal diamond are limited. With the development of chemical vapor deposition (CVD), however, the fabrication of single crystal diamond semiconductors at a reasonable production level is a real possibility. When large boules of high quality single crystal diamond are successfully developed by the CVD process, it is then generally necessary to slice the boules into semiconductor wafers for fabricating the single crystal diamond semiconductor devices.
Since diamond is the hardest known material, the abrasive cutting required to slice the wafers from the large single crystal boules is an extremely slow process. The use of lasers for cutting diamond wafers has generally been shown to be the most effective method at the present time. In a diamond cutting process, it is believed that an increase in the impurity level of the single crystal diamond reduces the diamond to diamond bonds in the lattice structure, and therefore, the effectiveness of the cutting may increase. However, as the impurity level of the diamond increase, the efficiency of the diamond material to act as a semiconductor device diminishes. Consequently, it appears a trade-off arises between high purity diamond and effectiveness of slicing the diamond boules.
What is needed then is a method of successfully slicing high purity single crystal diamond semiconductor boules into semiconductor wafers. It is therefore an object of the present invention to provide such a method.